The aim of the project is to research the climatic effects of the expected changes in the ecosystem. Here the hypothesis is that the change from tundra to grassland will result in a raised ratio of energy emission to energy absorption of the area, leading to less thawing of permafrost and thereby less emission of greenhouse gases.[8][9] It is also thought that removal of snow by large herbivores will further reduce the permafrost's insulation.

To study this, large herbivores have been released, and their effect on the local fauna is being monitored. Preliminary results point at the ecologically low-grade tundra biome being converted into a productive grassland biome, and at the energy emission of the area being raised.[10]

A documentary is being produced about the park by an American journalist and filmmaker.[11][12]

Researching the effects of large herbivores on the arctic tundra/grasslands ecosystem[edit]

The primary aim of Pleistocene Park is to recreate the mammoth steppe (ancient taiga/tundra grasslands that were widespread in the region during the last ice age). The key concept is that animals, rather than climate, maintained that ecosystem. Reintroducing large herbivores to Siberia would then initiate a positive feedback loop promoting the reestablishment of grassland ecosystems. This argument is the basis for rewilding Pleistocene Park's landscape with megafauna that were previously abundant in the area, as evidenced by the fossil record.[8][9][13]

The grassland-steppe ecosystem that dominated Siberia during the Pleistocene disappeared 10,000 years ago and was replaced by a mossy and forested tundra and taiga ecosystem.[8] Concurrently, most of the large herbivores that roamed Siberia during the Pleistocene have vanished from the region.[9] The mainstream explanation for this used to be that at the beginning of the Holocene the arid steppe climate changed into a humid one, and when the steppe vanished so did the steppe's animals.[8] Sergei Zimov points out that in contradiction to this scenario:

Those large herbivores of the former steppe that survived until today (e.g. musk oxen, bison, horses) thrive in humid environments just as well as in arid ones,[8][9][13]

The climate (both temperatures and humidity) in today's northern Siberia is in fact similar to that of the mammoth steppe. The radiation aridity index for northern Siberia on Mikhail Budyko's scale is 2 (= steppe bordering on semi-desert).[8][9][13]Budyko's scale compares the ratio of the energy received by the earth's surface to the energy required for the evaporation of the total annual precipitation. The 'humid climate' argument was based on other scales, which compare precipitation to potential evapotranspiration. Moss has a very low transpiration rate and thus causes humidity without necessarily needing humidity for its establishment. Using these other scales as a proof for humidity being the cause of the disappearance of the grasslands therefore constitutes a circular argument, which is not scientifically viable.

Zimov and colleagues argue for a reversed order of environmental change in the mammoth steppe. Humans, with their constantly improving technology, overhunted the large herbivores and led to their extinction and extirpation.[8][9][13][14] Without herbivores grazing and trampling over the land, mosses, shrubs and trees were able to take over and replace the grassland ecosystem.[8][9][13][14] If the grasslands were destroyed because herbivore populations were decimated by human hunting, then "it stands to reason that those landscapes can be reconstituted by the judicious return of appropriate herbivore communities."[8]

Researching the effects of large herbivores on permafrost and global warming[edit]

A secondary aim is to research the climatic effects of the expected changes in the ecosystem. Here the key concept is that some of the effects of the large herbivores, such as eradicating trees and shrubs or trampling snow, will result in a stronger cooling of the ground in the winter, leading to less thawing of permafrost during summer and thereby less emission of greenhouse gases.[8][9][11][13][15]

Permafrost is a large global carbon reservoir that has remained frozen throughout much of the Holocene.[16] Due to recent climate change, the permafrost is beginning to thaw, releasing stored carbon and forming thermokarst lakes.[16][17] When the thawed permafrost enters the thermokarst lakes, its carbon is converted into carbon dioxide and methane and released into the atmosphere.[18][19][20]Methane is a potent greenhouse gas and the methane emissions from thermokarst lakes have the potential to initiate a positive feedback cycle in which increased atmospheric methane concentrations lead to amplified global climate change, which in turn leads to more permafrost thaw and more methane and carbon dioxide emissions.[19][20]

As the combined carbon stored in the world's permafrost (1670 Gt)[21] equals about two times the amount of the carbon currently released in the atmosphere (720 Gt),[22] the setting in motion of such a positive feedback cycle could potentially lead to runaway climate change scenario. Even if the ecological situation of the arctic were as it was 400,000 years ago (i.e., grasslands instead of tundra), a global temperature rise of 1.5 °C (2.7 °F) relative to the pre-industrial level would be enough to start the thawing of permafrost in Siberia.[23] An increased cooling of the ground during winter would raise the current tipping point, potentially delaying such a scenario.

It has been proposed that the introduction of a variety of large herbivores will recreate their ancient ecological niches in Siberia and regenerate the Pleistocene terrain with its different ecological habitats such as taiga, tundra, steppe and alpine terrain.

The main object, however, is to recreate the extensive grasslands that covered the Beringia region in the late Pleistocene. This form of grassland (also known as mammoth steppe) was inhabited by a diverse set of large and medium herbivores. Back in the Pleistocene the area was populated by many species of grazers that assembled in large herds similar in size to those in Africa today. Species that roamed the great grasslands included the woolly mammoth, woolly rhino, steppe wisent, Lena horse, muskox, and reindeer.

Another herbivore that was abundant in this region during the Pleistocene but now faces possible extinction in its remaining habitats is the saiga antelope, which can form massive herds that keep the vegetation down.

At the edges of these large stretches of grassland could be found more shrub-like terrain and dry conifer forests (similar to taiga). In this terrain the browsers of the Pleistocene were to be found. This group of megafauna included woolly rhinoceros, moose, wapiti, Yukon wild ass, and camels. The more mountainous terrain was occupied by several species of mountain-going animals like the snow sheep.

Back in the Pleistocene there was also a great variety of carnivorous mammals as well. On the plains there were prides of Beringian cave lion. These large cats were the apex predators of the region, but also shared their habitat with other predators such as grey wolf, cave hyena, Homotherium, brown bear, wolverine, and Arctic fox, which all occupied a distinct ecological niche essential for the balance of their respective ecosystems.

In present-day Siberia only a few of the former species of megafauna are left, and their population density is extremely low, too low to affect the environment. To reach the desired effects, the density has to be raised artificially by fencing in and concentrating the existing large herbivores. A large variety of species is important as each species affects the environment differently and as the overall stability of the ecosystem increases with the variety of species[8] (compare Biodiversity#Biodiversity and ecological services). Their numbers will be raised by reintroducing species that went locally extinct (e.g., muskoxen). For species that went completely extinct, suitable replacements will be introduced if possible (e.g., wild Bactrian camels for the extinct Pleistocene camels of the genus Paracamelus). As the number of herbivores increases, the enclosure will be expanded.[8][9][24][25]

While this is taking place, the effects will be monitored. This concerns for example the effects on the flora (are the mosses being replaced by grasses, etc.), the effects on the atmosphere (changes in levels of methane, carbon dioxide, water vapor) and the effects on the permafrost.[10][26][27]

Finally, once a high density of herbivores over a vast area has been reached, predators larger than the wolves will have to be introduced to keep the megafauna in check.[8][9]

In 1996 a 50 ha (125 acre) enclosure was built in Pleistocene Park.[9] As a first step in recreating the ancient landscape, the Yakutian horses were introduced, as horses had been the most abundant ungulates on the northeastern Siberian mammoth steppe.[28] Of the first 40 horses, 15 were killed by predators and 12 died of eating poisonous plants. More horses were imported, and they learned to cope with the environment.[26] In 2006 approximately 20 horses lived in the park,[29] and by 2007 more horses were being born annually than died.[26] By 2013, the number had risen to about 30.[30] Moose, present in the area, were also introduced.[31] The effects of large animals (mammoths and wisents) on nature were artificially created by using an engineering tank and an 8-wheel drive Argo all-terrain vehicle to crush pathways through the willow shrub.[14][32][33][34]

Restored grasslands in Pleistocene Park

The vegetation in the park started to change. In the areas where the horses grazed, the soil has been compacted[27] and mosses, weeds and willow shrub were replaced by grasses.[3][10][25][35] Flat grassland is now the dominating landscape inside the park.[34] The permafrost was also influenced by the grazers. When air temperature sank to –40 °C (–40 °F) in winter, the temperature of the ground was found to be only –5 °C (+23 °F) under an intact cover of snow, but –30 °C (–22 °F) where the animals had trampled down the snow. The grazers thus help keep permafrost intact, thereby lessening the amount of methane released by the tundra.[10][13]

2004–2011

In the years 2004–2005 a new fence was erected, creating an enclosure of 16 km2 (6 sq mi).[25][36]

The new enclosure finally allowed a more rapid development of the project.[25] After the fence was completed, reindeer were brought into the park from herds in the region and are now the most numerous ungulates in the park.[31][37] To increase moose density in the park, special constructions were added to the fence in several places that allow animals outside the fenced area to enter the park, while not allowing them to leave. Besides that, wild moose calves were caught in other regions and transported to the park.[38]

In 2007 a 32-meter (105-foot) high tower was erected in the park that constantly monitors the levels of methane, carbon dioxide and water vapor in the park's atmosphere.[26][39]

In the years 2011 to 2016 progress slowed down as most energy was put into the construction of a 150 ha (370 ac) branch of Pleistocene Park near the city of Tula in Tula Oblast in Europe,[30][43] see below (Wild Field section). A few more reindeer and moose were introduced into Pleistocene Park during this time,[43][44] and a monitoring system for measuring the energy balance (ratio of energy emission and energy absorption)[note 1] of the pasture was installed.[45][46]

2017–

Attention has now been shifted back to the further development of Pleistocene Park. A successful crowdfunding effort in early 2017 provided funding for further animal acquisitions.[47][48][49] Later that year twelve domestic yak[50][51] and 30 domestic sheep[52][53] were brought to the park. The introduction of a herd of 12 plains bison is planned for May 2018,[54][55] and the introduction of more muskoxen is planned for 2019.[56]

For the near future the focus in animal introductions will generally be placed on browsers, not grazers, i.e., bison, muskoxen, moose and wapiti. Their role in this phase will be to diminish the amount of shrubs and trees and enlarge the grassy areas. Only when these areas have sufficiently increased will grazers like saiga and kiang be introduced.[57][58]

Critics admonish that introducing alien species could damage the fragile ecosystem of the existing tundra. To this criticism Sergey Zimov replied: "Tundra – that is not an ecosystem. Such systems had not existed on the planet [before the disappearance of the megafauna], and there is nothing to cherish in the tundra. Of course, it would be silly to create a desert instead of the tundra, but if the same site would evolve into a steppe, then it certainly would improve the environment. If deer, foxes, bovines were more abundant, nature would only benefit from this. And people too. However, the danger still exists, of course, you have to be very careful. If it is a revival of the steppes, then, for example, small animals are really dangerous to release without control. As for large herbivores – no danger, as they are very easy to remove again."[59]

Another point of concern is doubt that the majority of species can be introduced in such harsh conditions. For example, according to some critics, the Yakutian horses, although they have been living in the park for several generations, would not have survived without human intervention. They normally tolerate –60 °C, but are said to cope poorly with an abundance of snow and possibly would have died within the first snowy winter of starvation. However, horses of much less primitive stock abandoned by the Japanese Army have been living feral on some uninhabited Kuril Islands since 1945. Despite the deep snows (two to three times deeper than in Yakutia), they have successfully survived all the winters without feeding. And in Pleistocene Park, while some of the Yakutian horses accept supplementary feeding, others keep away and survive on their own.[26]

The Zimov’s concept of Pleistocene Park and repopulating the mammoth steppe is listed as one of the “100 most substantive solutions to global warming” by Project Drawdown.[60] The list, encompassing only technologically viable, existing solutions, was compiled by a team of over 200 scholars, scientists, policymakers, business leaders and activists;[61][62] for each solution the carbon impact through the year 2050, the total and net cost to society, and the total lifetime savings were measured and modelled.[63][64]

The park is a hub for international scientists and students, who come from around the world to conduct their own ecological research and experiments.[10] The Polaris Project was a yearly visitor from 2009 to 2015, sending US-American students on excursions to the park each summer.[65]

Another group of visitors are journalists. The park is steadily gaining more media attention and while most journalists do not come to the park itself the number of visitors is increasing. In 2016 for example, the park was visited by a filmmaker, two print media (Swiss 24 Heures and American The Atlantic), and two TV broadcasting companies (German ARD and American HBO).[66]

Pleistocene Park is owned and administered by a non-profit corporation, the Pleistocene Park Association, consisting of the ecologists from the Northeast Science Station in Chersky and the Grassland Institute in Yakutsk.[68] The present park area was signed over to the association by the state and is exempt from land tax.[5] The reserve is surrounded by a 600 km2 buffer zone that will be added to the park by the regional government once the animals have successfully established themselves.[68]

In July 2015 the Pleistocene Park Foundation was founded, a non-profit organization (registered in Pennsylvania, USA, with 501(c)(3) status)[69] dedicated to acquiring private donations for funding Pleistocene Park.[70] Hitherto Pleistocene Park had been financed solely through the funds of the founders, a practice that grew increasingly insufficient.[70]

Reindeer (Rangifer tarandus):[37] Present before the project started (although more are being brought to help simulate Pleistocene conditions). They mainly graze in the southern highlands of the park. This territory is not affected by spring flooding and dominated by larch forests and shrubland. Reindeer rarely visit the flood plain. Besides actively grazing (especially in winter) they browse on willow shrubs, tree moss, and lichens. (Numbers in park in July 2017: approximately 20)[71]

Elk[BE]/moose[AE] (Alces alces):[38] Present before the project started, although in low numbers. Immigration from neighboring areas is stimulated. Due to poaching the density of moose in the region has substantially decreased in the last 20 years. To increase moose density in the park, special constructions were added to the fence in several places that allow animals outside the fenced area to enter the park, while not allowing them to leave. Besides that wild moose calves are being caught in other regions and transported to the park.[38] It is the largest extant species of the deer family and one of the largest herbivores in the park today. (Numbers in park in July 2017: approximately 15)[71]

Yakutian horse (a domestic breed of Equus ferus caballus):[72] The first species to be introduced for the project, they were imported from the surrounding Srednekolymsk region beginning in 1988.[72] Yakutian horses have developed a range of remarkable morphologic, metabolic and physiologic adaptions to the harsh environment of Siberia, including an extremely dense and long winter coat, a compact build, a metabolism adjusted to seasonal needs, and an increased production of antifreezing compounds.[73][74] In summer they grow very large hooves, which they wear down in winter scraping away snow to get at food. Despite their size, they proved to be dominant over the wisents, who often fled from them. Yakutian horses are purely grazing animals – they eat only grass species, and visit the park's forests only during the spring flood. In the spring of 2015, ten more Yakutian horses were acquired to increase genetic diversity.[75] (Numbers in park in May 2018: approximately 30)[5]

Muskox (Ovibos moschatus):[76] Muskoxen arrived at the park in September 2010. They were brought from Wrangel Island[76] (itself repopulated with animals from North America). They are doing well and are now fully grown. Unfortunately only males could be acquired, and the Zimovs are now urgently looking for females.[40] The introduction of more muskoxen is planned for 2019.[56] (Numbers in park in July 2017: 3 males)[71]

Wisent (European bison, Bison bonasus):[77] During the last ice age, wisents were the most cold-adapted of the Bison species and thrived in the glacial grassland-steppe biome.[78][note 3] Their dietary needs are very different from the American bison. Year-round 10% of their intake necessarily consists of trees and shrubs, and they will ignore their main forage (grasses, sedges and forbs) in favour of woody forage to reach this quota.[79] Without supplementary feeding in winter, the yearly average may rise to 20% even in countries with mild winters.[80] Five wisents, one adult male and four juvenile females, were introduced in the park in April 2011. The wisents were brought to the park from the Prioksko-Terrasny Nature Reserve near Moscow.[42][77] The transportation was more complicated and took a longer time than originally thought, but all the animals recovered rapidly after the trip. Unfortunately, the wisents did not sufficiently acclimatize in the first months. They started to moult in November, when temperatures already were down to –30 °C (–35 °F) in Cherskii. The four juveniles died; only the adult bull survived. He is now fully acclimatized.[30][81] (Numbers in park in July 2017: 1 male)[71]

Wolverine (Gulo gulo): Present before the project started.[8][9] A stocky and muscular carnivore, the wolverine is a powerful and versatile predator and scavenger.

Red fox (Vulpes vulpes): Present before the project started.[8] Red foxes are omnivores with a highly varied diet. In the former Soviet Union, up to 300 animals and a few dozen plant species are known to be consumed by them.

Plains bison (Bison bison bison): Twelve yearling plains bison, nine males and three females,[90] have been acquired and will be introduced in the park once the United States’ FAA gives clearance for the flight.[4][91] The plains bison were bought from the Stevens Village Bison Reserve[note 4] near Delta Junction in Alaska; as the climate there is comparable to that of Siberia, the young bison are expected to thrive.[95] Plains bison are grazers of grasses and sedges. Unlike wisents, plains bison are almost pure grazers, which will consume other plant material mainly in time of need.[96][97][98] While wood bison were the preferred choice of subspecies, they are not easy to acquire;[81][99] plains bison simply are the subspecies that could be brought to the Park most easily.[48][100] (Numbers being introduced as of June 2018: 9 males, 3 females)[90]

Altai wapiti or Altai maral (Cervus canadensis sibiricus): Had been introduced in April 2011.[106] The wapiti made their way to the park all the way from the mountainous regions of Altai in central southern Siberia.[106] Wapiti are very good jumpers and all six escaped within the first two years. The fence has been strengthened to cope with future introductions.[15][44]

Wild yak (Bos mutus): Could be brought from the Tibetan Plateau. Along with the bison, horse, and reindeer, the species could contribute to the further proliferation of grasses in the region.[15][107]

Snow sheep (Ovis nivicola): Immigration from neighboring areas is encouraged. Especially rams may be lured to the park by domestic ewes in rut.[citation needed]

Saiga antelope (Saiga tatarica): Introduction is in the planning stage.[citation needed] Its presence would be critical for the regulation of poisonous plants in the region that can be digested by the saiga but are harmful to other herbivores. Currently, free saigas can only be found in Russia in the Chyornye Zemli Nature Reserve.

Siberian tiger (Panthera tigris altaica): Introduction planned for a later stage, when herbivores have multiplied.[8][9][26] Endangered and reduced to the Primorye region. As the largest feline alive, the Siberian tiger could play a key role in regulating the numbers of the largest herbivores.

Animals that could be placed in the park in the event of being 'resurrected' from extinction:

Woolly mammoth (Mammuthus primigenius): In January 2011, the Yomiuri Shimbun reported that a team of scientists from Kyoto University were planning to extract DNA from a mammoth carcass preserved in a Russian laboratory and insert it into egg cells of elephants in hope of creating a mammoth embryo. If the experiment succeeded, the calf would be taken to the park along with others to form a wild population. The researchers claimed that their aim was to produce the first mammoth within six years.[107][110][111][112][113]

Southern branch of Pleistocene Park: The Wild Field wilderness reserve[edit]

In 2012 to 2014 a branch of Pleistocene Park named "Wild Field" (Russian: Дикое полеDikoe pole) was constructed near the city of Tula in Tula Oblast in the European part of Russia, approximately 250 km (150 mi) south of Moscow.[30][114]

Unlike Pleistocene Park, Wild Field's primary purpose is not scientific research but public outreach, i.e., it will provide a model of what an unregulated steppe ecosystem looked like before the advent of humans. It is situated near a federal road and a railway station and will be accessible to the general public.[114]

^Wikipedia has no good basic article or at least article section on the energy balance (ratio of energy emission and energy absorption) of land surfaces – what it is, what affects it, etc. Some information may be gleaned from the articles

Earth's energy budget, though this article deals with the geological energy balance of the whole earth and not of individual areas,

Albedo, which is the scientific term for the fraction of the Sun's radiation reflected from a surface, though this article deals with geological albedo only in passing and more from a physical than from a geological or ecological point of view, and it is one of those articles written in such a way that, if you do not know the topic beforehand, already the introductory paragraph may stymie you.

^A newer source talks of “around 14 thousand hectares” (140 km2),[5] but as the two older references[8][68] were written by Sergey Zimov himself while the newer source was written by a journalist, 160 km2 is more likely to be the correct number.

^Two bison species are known to have co-existed during that period in Eurasia, the steppe bison (Bison priscus, the ancestor of today’s American bison) and the ancestral form of today’s wisent. A study on the distribution of these two species in the Urals, the Caucasus and Western Europe found that population replacements between steppe bison and wisent occurred regularly in correlation “with major palaeoenvironmental shifts”, with the wisent being “associated with colder, more tundra-like landscapes and absence of a warm summer” while the steppe bison dominated during the warmer interstadials. During the Last Glacial Maximum the steppe bison disappeared from all of the area covered by the study, leaving only the wisent.[78]

^For information on the Stevens Village Bison Reserve see for example the website of the Stevens Village Community Improvement Corporation, subpage “Stevens Village Bison Reserve”;[92] the 2006 article “Stevens Village council launches bison project” in the Juneau Empire;[93] and the 2010 article “Other tribes restore buffalo ties” in the Casper Star-Tribune.[94]

^These are the roe deer of the Tula region, which were already present on the site of Wild Field reserve. The species is not certain, as roe deer were absent in much of European Russia throughout the 20th century and only reoccupied the area in the last decades. Judging by the IUCN distribution maps,[119] the roe deer of the Tula region should be European roe deer (Capreolus capreolus), with the westernmost extension of the range of the Siberian roe deer (Capreolus pygargus) ending approximately 500 km (300 mi) to the east.

^"Pleistocene Park Underway: Home for Reborn Mammoths?", National Geographic, May 17, 2005, retrieved 20 April 2009, During the last ice age northeastern Siberia remained a grassy refuge for scores of animals, including bison and woolly mammoths. Then, about 10,000 years ago, this vast ecosystem disappeared as the Ice Age ended. Now, though, the Ice Age landscape is on its way back, with a little help from the Russian scientists who have established "Pleistocene Park.

^ abAnna Meyer (2005), Hunting the double helix: how DNA is solving puzzles of the past, Allen & Unwin, ISBN978-1-74114-107-8, retrieved 20 April 2009, ... lies in the work of a Russian ecologist, Sergei Zimov, who hopes to recreate a 'mammoth steppe' in north-east Siberia, part of a 'Pleistocene Park'. Work on the project has begun, and so far there are horses, moose, reindeer and bison in the park. These animals are removing mosses and shrubs, ...

^Illinois State Museum (w/o date): “Bison, Bison bison.” In: Explore the Ice Age Midwest .....plants and animals of the Pleistocene, web resource of the Illinois State Museum. Retrieved 14 November 2017.

^Facebook: Pleistocene Park Movie (23 July 2014): ″Sergey Zimov and Terry Chapin arranged for Wood Bison to be shipped to Yakutia in 2006. Unfortunately the Yakutian government did not allow any bison to be released Pleistocene Park.″ Retrieved 29 August 2014.